CLEVELAND, Ohio -- Activists from across the country gathered in Cleveland last weekend for a conference focused on police use of force against black and brown people, race relations, economic justice and other related topics.

The three-day conference held at Cleveland State University kicked off a new campaign, Movement for Black Lives, which is fueled by national outrage over a series of deaths of minorities at the hands of police.

I'm glad the activists were here. Conferences can produce constructive dialogue and build an organization through which real policy changes can be achieved.

There was noticeable diversity, not just of race, among the attendees, something that's needed to achieve the stated goal of equal justice for all.

But the success of the conference was marred by the actions of some participants -- and stand in direct contradiction to the stated goals of the gathering. It was also spoiled by the actions of a police officer, which earned the conference and the city instant notoriety thanks to the social media.

Let me break down these incidents.

On Sunday afternoon, when supporters of Movement for Black Lives were leaving CSU, they saw Greater Cleveland RTA officers with a black teenage boy in handcuffs at a bus shelter at Euclid Avenue and East 24th Street.

The conference participants immediately assumed that the police - not the boy - had done something wrong and began rallying against the police, demanding to know why he was in handcuffs and that he be released.

Nobody could have known what was going on. But that didn't' seem to matter. The crowd fed on itself.

The RTA later explained that its officers had removed the boy - who they suspect was intoxicated -- without incident from a bus and sat him at shelter at Euclid Avenue and East 24th Street so they could get information from him and call his parents. The police officers said in a report that they found the teen on the bus passed out and drooling. He was cuffed as a matter of procedure.

As the crowd swelled, the police placed the boy in a police car for his safety, the RTA said in a statement. Then, protesters -- many of whom were filming the action on their cell phones - surrounded the RTA police car and prevented the police from moving the teen. (Normally, RTA officers take juveniles to police headquarters, where they are released to an adult.)

An RTA officer then did something stupid. He shot pepper spray at people blocking the patrol car -- a move that incited the crowd and played perfectly into the conference narrative about police. Several people were hit and were seen washing out their eyes with water, according to video of the incident posted online.

The officer's actions could easily have sparked a riot. I know a reasonable argument can be made that the officer was simply responding to people who refused police commands to back away. But we've seen this time and time again. Angry crowds respond better when police show humanity instead of force.

When an ambulance arrived to check on the teen boy, the crowd moved to allow him to be examined. As police walked him to the ambulance, the crowd chanted "Take them off, take them off" in reference to the handcuffs.

The teen was released to his mother, who arrived on scene, and the incident ended. But the video of the RTA officer spraying demonstrators went viral instantly.

This brings me to the second incident in which participants in the Movement for Black Lives hurt their credibility.

Brandon Blackwell, a crime reporter for the Northeast Ohio Media Group who frequently covers police and demonstrations, saw the pepper spray video and rushed to the scene.

When he arrived, the police were gone but the crowds remained. Blackwell then did what he always does. He started recording with his cell phone and asking questions. On Sunday, he used Twitter's Periscope app to broadcast the scene live.

But the crowd turned on Blackwell as he filmed a large group gathered in a circle on a sidewalk outside of a CSU building. A man announced the circle was only for people of "African descent."

Blackwell, who is white, was dressed in his daily uniform of jeans, a black T-shirt and Converse shoes. He stepped outside the circle and continued to record. Then, people began blocking his camera with shirts, theirs hands, signs and other objects, including an orange traffic cone.

Some people offered absurd explanations for why he couldn't film the rally, which was going on in open view and on public property. One said Blackwell could be a federal agent. Another said he endangered the children among the group who could be identified and targeted by police. Another suggested Blackwell, who has large cross tattoo on his inner arm, could be a white supremacist. One woman, shouted, "People don't want to be recorded."

Blackwell, while he didn't like it, knew the crowd was within its rights to block his camera's view. He also knew he was well within his rights to try to record the action. That's journalism. No different than recording how police handle protesters, which he has done. No different than demanding access to court hearings to ensure justice is administered fairly for all.

But Blackwell objected when some people tried to touch him and his equipment.

During one of the tense moments in the exchange, Blackwell demanded that those blocking his view not touch his camera.

"I got 800 black people behind me, what the f--- you going to do," a man responded, getting in Blackwell's face while continuing to block his camera.

Blackwell asked for someone to get the guy away from him, but more people came at Blackwell instead.

Just then, Blaine Griffin, the head of Cleveland's community relations board, arrived and admonished the crowd to back up.

Blackwell turned off his camera when a couple of people agreed to talk but only off camera.

Much of the Blackwell's interaction can be seen in the videos posted on this page. You can watch the pepper spray incident here.

RTA should be concerned by the actions of its officer. RTA promises to fully investigate -- and it should. The officer's actions could have made things much worse.

The Movement for Black Lives should be embarrassed by the actions of some of its supporters. Their quick judgment toward police and their prejudiced and intolerant reactions to a reporter doing his job represent the very things they decry.